In my U.S. Pat. No. 4,649,922 a device is described in combination with a catheter which is basically a compression spring retained between a partially inflated balloon and an abutment immediately behind the balloon on the catheter shaft. The intent is to transport the spring prosthesis in this manner to the desired location and then after a successful angioplasty procedure release said spring prosthesis by totally evacuating said balloon, thus allowing said spring prosthesis to expand linearly and stay in place while the balloon catheter is withdrawn. This method is quite simple and its simplicity is very attractive; however it has some drawbacks. One and foremost is the fact that the spring has a fixed diameter and as such is unable to fully conform to the inside wall of the vessel which at times is quite tortuous and thus could conceivably create a somewhat turbulant flow of blood, and possible thrombosis could in some cases result. Other Patents, e.g. No. 4,553,545 teach a different method where a relatively complex mechanical rotating device and co-axial cables are employed to achieve the necessary means to change the diameter of the implanted stent to a larger dimension at the point of implant. Still other Patents, e.g. No. 3,868,956 describe a method wherein a temperature responsive metalic device is used and expanded after implant using external heat sources. All of the above mentioned devices present drawbacks of various magnitudes including blood coagulation and possble thrombosis, and considerable complexity of procedure.
In angioplasty procedures at this time, in many cases restenosis occures soon thereafter, which requires a secondary procedure or a surgical bypass operation. The implanted prosthesis as described herein will preclude such additional procedures and will maintain vascular patency indefinately.
Depending on the size used, the device according to this invention can also be efficacious in other, similar applications, such as: repair of aneurisms, support of artificial vessels or liners of vessels, stabilization of interior vessel tubes, e.g. bronchial tubes, retention of embolii and plaque and mechanical support to prevent collapsing of dialated vessels. Still many other and similar applications will be satisfied by this invention without departing from the basic premise and concept.
This device particularely allows a single percutaneous transluminal angioplasty procedure to combine the essential angioplasty itself using any standard balloon-type catheter to recanalize an obstructed vessel with the implantation of a permanent prosthesis stent in one single procedure thereby reducing the risk factor and the trauma by a considerable degree for the patient undergoing such procedure.
Other reference publications:
1. Self-expanding metalic stents for small vessels, Radiology 1987--162.469-472.
2. Intravascular stents to prevent to prevent occlusion and restenosis after transluminal angioplasty. N.E.J. of Med. Mar. 19, 1987. describes experiments with a stent on animals.
3. U.S. Pat. No. 4,580,568 Percutaneous endovascular stent.
4. U.S. Pat. No. 4,503,569 transluminally placed expandable graft prosthesis, Dotter 1985.
5. U.S. Pat. No. 4,699,922 Catheter arrangement having a variable diameter tip and spring prosthesis, Wiktor 1987.
All of the above references describe or teach various methods of providing or otherwise introducing stents or different types for applications similar to one described in this invention.